In the aforementioned patent, there is described a rapid-closing switch, especially for electrical circuits operating with voltages above 1000 volts and currents above 1000 amperes and in which, between the electrodes, there is disposed a U-shaped aluminum body which is replaceable and separated from at least one of the electrodes by a foil of insulating material. The switching electrode is juxtaposed with the counterelectrode and has sharp edges adapted to pierce the foil. Between the shanks of the U, there is provided an impulse source capable of being exploded, e.g. a fusible strip or a pair of closely spaced fusible strips, which can be connected to a source of electrical energy to generate the explosive or shock wave. Metal foils are closely spaced and are of equal spacing from the electrodes so that, upon explosive disintegration of the foils, the aluminum shanks of sheet metal of the U-shaped body are driven outwardly toward the switching and counter-electrodes. By rupture of the insulating foil, the aluminum body is driven against the switching electrode and brought into contact therewith.
As discussed in the aforementioned patent, each of the two metal foils is connected to an electrical-pulse source of high voltage and has a monotonically increasing cross section from its explosion-initiating part towards its connection with the source.
One of the improvements described in said patent resides in a groove formed in the switching electrode and open in the direction of the U-shaped body, this groove having a mouth whose width is narrower than the width of the base of the groove and receiving in the groove prismatic bars or ribs.
While the system described in this U.S. Pat. No. 3,641,289 has proved to be a major advance over the earlier arrangements, it has been found that the particular configuration of the bars in the grooves, with their transverse and longitudinal portions, have limited useful life and the breakdown voltage of the system under static conditions is low.